His father served as a private in the 30th Wisconsin Infantry Regiment in the Union Army during the Civil War.
In 1909–1911, Gillette served as an apprentice in the Boston office of Warren H. Manning, a leading early-20th century landscape architect.
During the 1950s, Gillette redesigned the gardens of Virginia's Executive Mansion at the request of Governor Thomas B. Stanley.
[1] A number of his works were designed for properties listed on the National Register of Historic Places.
[2] Author Tom Wolfe references Gillette as the commissioned landscaper of Dupont University in I Am Charlotte Simmons.